Tree shrews (Tupaia glis) raised with one eyelid sutured closed develop significant myopia (about 7 diopters) in the lid-sutured eye. An understanding of the mechanisms which produce the myopia in three shrew may lead to a better understanding of the mechanisms which produce myopia in humans. The small eye of the tree shrew makes accurate and reliable measures of the eyes difficult. The purpose of this pilot project will be to develop and assess reliable 1) keratoscopic methods, to assess changes in corneal curvature; 2) retinoscopic measures, to assess the degree of myopia; 3) A-scan ultrasonographic methods to non-invasively assess the overall length of the eyes and the size and placement of the lens; 4) focal length measures of the lens. Once reliable and valid measures of these ocular components have been developed in the pilot studies, a thorough assessment can be made of the ocular alterations which produce a myopia in lid-sutured tree shrews. Adaptations of these methods may allow study of the myopia as it develops in immature animals.